Table of Contents
I. Positivism as Dicta
II. Shifting the Source of Authority
A. Erie's Conception of Positivism
B. Mixed Conceptions of Positivism
1. Hart's Practice Version
2. Mixed Conceptions and Their Problems
III. Priority and Self-Executing Law
IV. Legal Argument About Customary
Customary international law is puzzling in a way treaties are untroubling. Treaties are contracts, and the source of the obligations they impose on states, as well their content, present no special legal problem. (1) If there is a puzzle about how treaties can bind states, it is a general puzzle about how contracts can legally bind promisors. By comparison, the status of customary international law is controversial. (2) Customary international law is law that "results from a general and consistent practice of states followed by them from a sense of legal obligation." (3) Because it is created by the regular practice of states, the extent of behavioral regularity required for a custom to exist is vague. Similarly, because customary international law does not have the canonical form of a treaty or statute, its content is uncertain. Even the extent to which states act merely in accordance with norms, rather than from a sense of obligation, is unknown and understudied. (4)
Customary international law has to answer a range of questions. May a state unilaterally withdraw from a treaty to which it is a party when the treaty does not otherwise provide for withdrawal? (5) Are states obligated to not arbitrarily detain people or subject them to degrading treatment? (6) May a successor state repudiate the odious debts of the preceding state? (7) Because customary international law is created by the regular practice among states, not by the states' lawmakers, (8) its legal validity is not self-evident. Three questions can therefore be asked in connection with its legal status: (1) What are the norms of customary international law governing the conduct of states and their citizens?; (2) Are states legally bound by customary international law?; and (3) Does customary international law apply domestically without incorporation by domestic law?
I will argue that there are other sorts of questions that do not need to be asked about customary international law--namely, jurisprudential ones. It is often thought that judicial recognition of customary international law depends on jurisprudential assumptions about the nature of law, legal norms, and legal validity. (9) This is a mistake. The limits of judicial reliance on customary international law are constitutional or evidentiary, not jurisprudential. (10) Jurisprudential views about law, which are analytic in character, have nothing to say about the questions posed above.
My argument follows in three steps. The first step is a claim about Erie Railroad Co. v. Tompkins. (11) Although Erie can fairly be read to require domestic authorization in order for customary international law to have domestic legal effect, the case and its reasoning do not rely on commitments to a theory of law, including legal positivism. Second, reliance on positivism has an unwelcome consequence for the binding character of customary international law. Third, conceptions of law or legal validity can ground different views about the relation between international and domestic law. Positions on the priority of customary international law are therefore determined by views about that relation, not by views on the source of its authority. Taken together, these considerations suggest that jurisprudence is not needed to answer the questions courts and other legal authorities ask about customary international law's content, the legal obligations it creates, and its domestic legal effect.
This Article is divided into four parts. Part I argues that legal positivism is irrelevant to Erie's holding that federal jurisdiction does not give federal courts general law-making power. …